A practical transmission scheme for half-duplex decode-and-forward MIMO relay channels

We propose a novel and practical transmission strategy for decode-and-forward MIMO relay channels operating in half-duplex mode that is based on precoding with time, power, and spatial stream allocation. In the proposed scheme, the message from the source is divided into two parts and sent to the destination, one part directly and the other with the help of the relay. We formulate the problem of finding the rate-maximizing precoding matrices and resource allocation and then transform it into a convex form by employing the proposed suboptimal but simplifying precoding structure and performing other manipulations. The numerical results show that the achievable rate of the proposed scheme is close to a well-known theoretical lower bound and even outperforms it in certain scenarios, despite our transmission strategy being based on a much simpler coding scheme. Additionally, the proposed scheme is able to outperform another scheme based on repetition coding with fixed time slot duration.